Compressor

ABSTRACT

A compressor includes a compression mechanism housed in a casing. The compression mechanism includes a suction volume adjustment mechanism capable of switching a suction completion position of a compression chamber in a suction process between a first position and a second position with a smaller suction volume than the first position. The suction volume adjustment mechanism includes a plunger switchable between a closed position in which the suction completion position is moved to the first position and an open position in which the suction completion position is moved to the second position. An oil passage is arranged to allow an oil reservoir formed inside the casing and a suction space of the compression chamber to communicate with each other. The plunger is disposed midway along the oil passage, and includes a switching portion closing the oil passage in the closed position, and opening the oil passage in the open position.

TECHNICAL FIELD

The present disclosure is directed to a compressor including a suctionbypass mechanism configured to change a position at which a suctionprocess is completed and a compression process is started (hereinafterreferred to as “suction completion position”) to adjust a suctionvolume. The present disclosure relates to a technique of solvinglubricant shortage in a compression mechanism.

BACKGROUND ART

In conventional compressors, inverters are widely used to allow thecompressors to be used in various operations ranging from an operationat a high rotational speed to an operation at a low rotational speed.Generally, during an operation at a high rotational speed, the flow rateof a refrigerant inside a compressor is increased. This increases theamount of refrigerating machine oil to be sucked together with therefrigerant to be supplied to a compression mechanism of the compressor,resulting in an increase in the amount of the refrigerating machine oilto be discharged together with the refrigerant compressed. Therefore, ithas been desired to reduce the amount of refrigerating machine oil to besupplied to the interior of the compression mechanism.

It has been suggested to provide a capacity adjusting mechanism to acompression mechanism in order to achieve performance of invertercontrol not only when a compressor is operated at a high rotationalspeed (hereinafter referred to as “the operation at the high operationcapacity”) but also when the compressor is operated at a low rotationalspeed (hereinafter referred to as “the operation at the low operationcapacity” (See Patent Document 1). At the low operation capacity, theoperation is generally performed at a low rotational speed, and itsperformance is lower at the low rotational speed than at the highrotational speed. In order to reduce performance degradation at the lowrotational speed, it is preferable to allow the capacity adjustingmechanism to reduce the suction volume to increase the rotational speed.

For example, Patent Document 1 discloses a suction bypass mechanismwhich adjusts a suction volume by changing a suction completion positionin a scroll compressor. The suction bypass mechanism of Patent Document1 includes a plunger (valve) serving as an opening/closing mechanismallowing first and second compression chambers to switch between acommunicating state and a shut-off state, the first compression chamberbeing provided between the inner peripheral surface of a fixed scrolland the outer peripheral surface of an orbiting scroll, and the secondcompression chamber being provided between the outer peripheral surfaceof the fixed scroll and the inner peripheral surface of the orbitingscroll. If this suction bypass mechanism allows the first and secondcompression chambers to communicate with each other, the suctioncompletion position is changed from the position of the shut-off stateto a position in which the suction volume is reduced. According to thisconfiguration, in a situation where the operation capacity issubstantially constant, a smaller suction volume allows the compressionmechanism to be operated at a high rotational speed. This can achieveits performance.

CITATION LIST Patent Document

[Patent Document 1] Japanese Unexamined Patent Publication No.2007-154761

SUMMARY OF THE INVENTION Technical Problem

However, in a situation where the compressor is controlled at a lowoperation capacity, if the compressor is tried to be rotated at a higherspeed than a situation where the capacity is not controlled, itsperformance can be less reduced than the situation where the capacity isnot controlled. However, oil to be supplied to the compression chamberis insufficient due to the low operation capacity, and an oil film isnot sufficiently formed inside the compression mechanism, resulting ininsufficient performance.

That is to say, if oil loss at the high rotation capacity is reduced,oil supply necessary for forming the oil film inside the compressionmechanism at the low operation capacity is also insufficient. Thus, inthe compressor, it is actually difficult to reduce performancedegradation at the low operation capacity and oil loss at the highoperation capacity.

In view of the foregoing background, it is therefore an object of thepresent disclosure to provide a technique of improving performance of acompressor at a low operation capacity while reducing oil loss at a highoperation capacity.

Solution to the Problem

A first aspect of the present disclosure is directed to a compressorincluding: a compression mechanism (20); and a casing (10) housing thecompression mechanism (20), the compression mechanism (20) including asuction volume adjustment mechanism (30) capable of switching a suctioncompletion position of a compression chamber (25 a, 25 b) in a suctionprocess between a first position and a second position in which thesuction volume is smaller than in the first position, the suction volumeadjustment mechanism (30) including a plunger (33) switchable between aclosed position in which the suction completion position is moved to thefirst position and an open position in which the suction completionposition is moved to the second position.

This compressor further includes an oil passage (51) to allow an oilreservoir (18, 50) formed inside the casing (10) and a suction space (25s) of the compression chamber (25 a, 25 b) to communicate with eachother, and the plunger (33) is disposed midway of the oil passage (51),and includes a switching portion (65) closing the oil passage (51) inthe closed position to allow the oil reservoir (18, 50) not tocommunicate with the suction space (25 s) of the compression chamber (25a, 25 b), and opening the oil passage (51) in the open position to allowthe oil reservoir (50) to communicate with the suction space (25 s) ofthe compression chamber (25 a, 25 b).

According to the first aspect, if the suction completion position is inthe first position, the plunger (33) is in the closed position. At thattime, the oil passage (51) is blocked, and thus, no oil is supplied fromthe oil reservoir (18, 50) to the suction space (25 s) of thecompression chamber (25 a, 25 b). In contrast, if the suction completionposition is in the second position, in which the suction volume isreduced, the plunger (33) is in the open position. At that time, the oilpassage (51) is opened, and thus, oil is supplied from the oil reservoir(18, 50) to the suction space (25 s) of the compression chamber (25 a,25 b) by a negative pressure in the suction space (25 s).

A second aspect of the present disclosure is an embodiment of the firstaspect of the present disclosure. In the second aspect, the compressionmechanism (20) is a compression mechanism (20) including a fixed scroll(21), and an orbiting scroll (22) meshing with the fixed scroll (21) andcompressing a working fluid.

According to the second aspect, if in the scroll compressor, the suctioncompletion position is in the first position and the plunger (33) is inthe closed position, the oil passage (51) is blocked. Thus, no oil issupplied from the oil reservoir (18, 50) to the suction space (25 s) ofthe compression chamber (25 a, 25 b). If the suction completion positionis in the second position and the plunger (33) is in the open positionin which the suction volume is reduced, the oil passage (51) is opened.Thus, oil is supplied from the oil reservoir (18, 50) to the suctionspace (25 s) of the compression chamber (25 a, 25 b) by the negativepressure.

A third aspect of the present disclosure is an embodiment of the secondaspect of the present disclosure. In the third aspect, the oil passage(51) has one end communicating with the oil reservoir (50) formed in acrank chamber (23 e) that is a space inside the housing (23) of thecompression mechanism (20), and the other end communicating with thesuction space (25 s) of the compression mechanism (20).

According to the third aspect, if the suction completion position is inthe second position and the suction volume is reduced, the plunger (33)is in the open position and the oil passage (51) is opened. Thus, oil issupplied from the oil reservoir (18, 50) formed in the space (the crankchamber (23 e)) inside the housing of the compression mechanism (20) tothe suction space (25 s) of the compression chamber (25 a, 25 b) by thenegative pressure.

A fourth aspect of the present disclosure is an embodiment of the secondaspect of the present disclosure. In the fourth aspect, the oil passage(51) includes an orbiting-scroll-side oil passage (55) and afixed-scroll-side oil passage (52) communicating with theorbiting-scroll-side oil passage (55), the orbiting-scroll-side oilpassage (55) has one end communicating with the fixed-scroll-side oilpassage (52), and the other end opposite to one end and communicatingwith the oil reservoir (50), and the fixed-scroll-side oil passage (52)has one end communicating with the orbiting-scroll-side oil passage(55), and the other end opposite to one end and communicating with thesuction space (25 s) of the compression mechanism (20).

According to the fourth aspect, if the suction completion position is inthe second position and the suction volume is reduced, the plunger (33)is in the open position and the oil passage (51) comprised of theorbiting-scroll-side oil passage (55) and the fixed-scroll-side oilpassage (52) is opened. Thus, oil is supplied from the oil reservoir(18, 50) to the suction space (25 s) of the compression chamber (25 a,25 b) by the negative pressure.

A fifth aspect of the present disclosure is an embodiment of the secondaspect of the present disclosure. In the fifth aspect, the oil passage(51) has an oil supply pipe (56) having one end communicating with theoil reservoir (18) formed inside the casing (10), and the other endcommunicating with the suction space (25 s) of the compression mechanism(20).

According to the fifth aspect, if the suction completion position is inthe second position and the suction volume is reduced, the plunger (33)is in the open position and the oil passage (51) is opened. Thus, oil issupplied from the oil reservoir (18, 50) formed in the casing (10) tothe suction space (25 s) of the compression chamber (25 a, 25 b) by thenegative pressure.

A sixth aspect of the present disclosure is an embodiment of the secondaspect of the present disclosure. In the sixth aspect, the oil passage(51) has an oil supply pipe (57) having one end communicating with anoil supply pump (43 a) provided to a drive shaft of the compressionmechanism (20), and the other end communicating with the suction space(25 s) of the compression mechanism (20).

According to the sixth aspect, if the suction completion position is inthe second position and the suction volume is reduced, the plunger (33)is in the open position and the oil passage (51) is opened. Thus, oil issupplied from the oil supply pump (43 a) to the suction space (25 s) ofthe compression chamber (25 a, 25 b).

A seventh aspect of the present disclosure is an embodiment of any oneof the third to sixth aspects of the present disclosure. In the seventhaspect, the oil passage (51) has a fixed scroll inner passage (53)passing through an interior of the fixed scroll (21) to communicate withthe plunger (33) and the suction space (25 s) of the compressionmechanism (20).

According to the seventh aspect, if the suction completion position isin the second position and the suction volume is reduced, the plunger(33) is in the open position and the oil passage (51) is opened. Thus,oil is supplied to the suction space (25 s) of the compression chamber(25 a, 25 b) through the fixed scroll inner passage (53) in the interiorof the fixed scroll (21).

An eighth aspect of the present disclosure is an embodiment of any oneof the third to sixth aspects of the present disclosure. In the eighthaspect, the oil passage (51) has a fixed scroll outer passage (58)passing through a space formed outside the fixed scroll (21) and insidethe casing (10) to communicate with the plunger (33) and the suctionspace (25 s) of the compression mechanism (20).

According to the eighth aspect, if the suction completion position is inthe second position and the suction volume is reduced, the plunger (33)is in the open position and the oil passage (51) is opened. Thus, oil issupplied from the oil reservoir (18, 50) formed in the casing (10) tothe suction space (25 s) of the compression chamber (25 a, 25 b) throughthe space formed outside the fixed scroll (21) and inside the casing(10).

A ninth aspect of the present disclosure is an embodiment of any one ofthe third to sixth aspects of the present disclosure. In the ninthaspect, the suction volume adjustment mechanism (30) has a dischargepassage (60) discharging the working fluid from the plunger (33) in thesecond position into a space formed outside the fixed scroll (21) andinside the casing (10), and the oil passage (51) has an oil mix passage(53 a) having one end communicating with the plunger (33), and the otherend communicating with the discharge passage (60).

According to the ninth aspect, if the suction completion position is inthe second position and the suction volume is reduced, the plunger (33)is in the open position and the oil passage (51) including the oil mixpassage (53 a) communicating with the discharge passage (60) is opened.Thus, oil is supplied from the oil reservoir (18, 50) formed in thecasing (10) to the suction space (25 s) of the compression chamber (25a, 25 b) through the space formed outside the fixed scroll (21) andinside the casing (10).

A tenth aspect of the present disclosure is an embodiment of any one ofthe one to ninth aspects of the present disclosure. In the tenth aspect,the plunger (33) is a cylindrical valve body, and has an outer surfaceprovided with a circumferential groove (33 d) that is disposed on theoil passage (51) in the second position and is deviated from the oilpassage (51) in the first position.

An eleventh aspect of the present disclosure is an embodiment of thetenth aspect of the present disclosure. In the eleventh aspect, theplunger (33) includes a sealing member (33 e) at both sides of thecircumferential groove (33 d) formed in the outer surface of the plunger(33).

Advantages of the Invention

According to the first aspect of the present disclosure, if the suctioncompletion position is in the first position and no capacity control isperformed, the plunger (33) is in the closed position to block the oilpassage (51). This operation is the operation performed a high operationcapacity, and the flow rate of the refrigerant inside the compressor isincreased. Thus, oil is sufficiently sucked into the compressionchambers (25 a, 25 b) and excessive oil is not supplied from the oilpassage (51) to the compression chambers (25 a, 25 b). This reduces oilloss while maintaining its performance.

In contrast, if the suction completion position is in the secondposition and the capacity is controlled such that the suction volume isreduced, the plunger (33) is in the open position and the oil passage(51) is opened. This operation is the operation performed a lowoperation capacity, and the flow rate of the refrigerant inside thecompressor is decreased. Therefore, although oil mixed in therefrigerant is insufficiently sucked into the compression chambers (25a, 25 b), oil is supplied from the oil passage (51) to the compressionchambers (25 a, 25 b) as well. According to the first aspect of thepresent disclosure, at that time, the oil film can be sufficientlyformed in the interior of the compression mechanism, compared to thecase where the capacity of the compressor is not controlled. This canimprove performance of the compressor.

According to the second aspect of the present disclosure, in the scrollcompressor, if the suction completion position is in the first positionand no capacity control is performed, the plunger (33) is in the closedposition to block the oil passage (51). This operation is the operationperformed a high operation capacity, and the flow rate of therefrigerant inside the compressor is increased. Thus, oil issufficiently sucked into the compression chambers (25 a, 25 b) andexcessive oil is not supplied from the oil passage (51) to thecompression chambers (25 a, 25 b). This reduces oil loss whilemaintaining its performance.

In contrast, if the suction completion position is in the secondposition and the capacity is controlled such that the suction volume isreduced, the plunger (33) is in the open position and the oil passage(51) is opened. This operation is the operation performed a lowoperation capacity, and the flow rate of the refrigerant inside thecompressor is decreased. Therefore, although oil mixed in therefrigerant is insufficiently sucked into the compression chambers (25a, 25 b), oil is supplied from the oil passage (51) to the compressionchambers (25 a, 25 b) as well. According to the second aspect of thepresent disclosure, at that time, the oil film can be sufficientlyformed in the interior of the compression mechanism, compared to thecase where the capacity of the compressor is not controlled. This canimprove performance of the compressor.

According to the third aspect of the present disclosure, oil can besupplied to the compression chambers (25 a, 25 b) during adjustment ofthe suction volume using the oil passage (51) having one endcommunicating with the oil reservoir (18, 50) formed in the space insidethe housing (23) of the compression mechanism (20) (the crank chamber(23 e)), and the other end communicating with the suction space (25 s)of the compression mechanism (20). Therefore, this can improveperformance of the scroll compressor with a simple configuration.

According to the fourth aspect of the present disclosure, oil can besupplied to the compression chambers (25 a, 25 b) during adjustment ofthe suction volume, using the oil passage (51) comprised of theorbiting-scroll-side oil passage (55) and the fixed-scroll-side oilpassage (52), and having one end communicating with the oil reservoir(18, 50) and the other end communicating with the suction space (25 s)of the compression mechanism (20). Therefore, this can reduceperformance degradation of the scroll compressor and oil loss with asimple configuration.

According to the fifth aspect of the present disclosure, oil can besupplied to the compression chambers (25 a, 25 b) during adjustment ofthe suction volume using the oil passage (51) having one endcommunicating with the oil reservoir (18, 50) formed in the casing (10)of the compressor, and the other end communicating with the suctionspace (25 s) of the compression mechanism (20). Therefore, this canimprove performance of the scroll compressor with a simpleconfiguration.

According to the sixth aspect of the present disclosure, oil can besupplied to the compression chambers (25 a, 25 b) during adjustment ofthe suction volume using the oil passage (51) having one endcommunicating with the oil supply pump (43 a), and the other endcommunicating with the suction space (25 s) of the compression mechanism(20). Therefore, this can improve performance of the scroll compressorwith a simple configuration.

According to the seventh aspect of the present disclosure, oil can besupplied to the compression chambers (25 a, 25 b) during adjustment ofthe suction volume using the oil passage (51) having the fixed scrollinner passage (53) passing through the inside of the fixed scroll (21)to communicate with the plunger (33) and the suction space (25 s) of thecompression mechanism (20). Therefore, this can improve performance ofthe scroll compressor with a simple configuration.

According to the eighth aspect of the present disclosure, oil can besupplied to the compression chambers (25 a, 25 b) during adjustment ofthe suction volume using the oil passage (51) having the fixed scrollouter passage (58) passing through the space formed outside the fixedscroll (21) and inside the casing (10) to communicate with the plunger(33) and the suction space (25 s) of the compression mechanism (20).Therefore, this can improve performance of the scroll compressor with asimple configuration.

According to the ninth aspect of the present disclosure, oil can besupplied to the compression chambers (25 a, 25 b) during adjustment ofthe suction volume using the oil passage (51) having the oil mix passage(53 a) communicating with the discharge passage (60) discharging theworking fluid from the plunger (33) into the space formed outside thefixed scroll (21) and inside the casing (10). Therefore, this canimprove performance of the scroll compressor with a simpleconfiguration.

According to the tenth aspect of the present disclosure, a suctionvolume adjustment mechanism (30) can be provided with a simpleconfiguration having the plunger (33) that is a cylindrical valve body.According to the eleventh aspect of the present disclosure, the plunger(33) is provided with the sealing member (33 e), thereby making itpossible to reduce oil leakage.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a vertical cross-sectional view of a compressor according to afirst embodiment.

FIG. 2 illustrates the shape of a fixed scroll and the shape of anorbiting scroll in a cross-section taken along line II-II of FIG. 1.

FIG. 3 is an enlarged cross-sectional view of a compression mechanism.

FIG. 4 illustrates a cross-sectional structure of an opening/closingmechanism.

FIG. 5 is an enlarged front view of a plunger.

FIG. 6 is a plan view illustrating the shape of a transverse passage ofan oil passage.

FIG. 7 illustrates the compression mechanism in a first operation state.

FIG. 8 illustrates the compression mechanism in a second operationstate.

FIG. 9 illustrates the compression mechanism in a third operation state.

FIG. 10 illustrates the compression mechanism in a fourth operationstate.

FIG. 11 illustrates the compression mechanism in a fifth operationstate.

FIG. 12 illustrates the compression mechanism in a sixth operationstate.

FIG. 13 illustrates a cross-sectional structure of a compressionmechanism according to a variation of the first embodiment.

FIG. 14 is a plan view of the fixed scroll of the compression mechanismof FIG. 3.

FIG. 15 is a vertical cross-sectional view of a compressor according toa second embodiment.

FIG. 16 is an enlarged cross-sectional view of a compression mechanismin FIG. 15.

FIG. 17 is a vertical cross-sectional view of a compressor according toa third embodiment.

FIG. 18 is a vertical cross-sectional view of a compressor according toa fourth embodiment.

FIG. 19 is a plan view of a compressor according to a fifth embodiment.

FIG. 20 is a cross-sectional view illustrating a first state of aplunger of the compression mechanism of FIG. 19.

FIG. 21 is a cross-sectional view illustrating a second state of theplunger of the compression mechanism of FIG. 19.

FIG. 22 is a plan view of a compressor according to a sixth embodiment.

FIG. 23 is a cross-sectional view illustrating a configuration for theplunger of the compression mechanism of FIG. 22.

FIG. 24 is an enlarged view of a plunger according to a variation.

DESCRIPTION OF EMBODIMENTS

Embodiments of the present disclosure will now be described in detailwith reference to the drawings.

First Embodiment

A first embodiment of the present disclosure is now described.

A scroll compressor according to this embodiment is provided to, e.g., arefrigerant circuit of an air conditioner performing a vapor compressionrefrigeration cycle, and compresses a low-pressure refrigerant that hasbeen sucked from an evaporator to discharge it into a condenser.

As illustrated in FIG. 1, the scroll compressor (1) is a so-calledhermetic compressor. This scroll compressor (1) includes a casing (10)that is a hermetically-sealed container with a vertically orientedcylindrical shape. The casing (10) includes a body (11) with avertically oriented cylindrical shape, an upper end plate (12) fixed tothe upper end of the body (11), and a lower end plate (13) fixed to thelower end of the body (11).

This casing (10) houses a compression mechanism (20) compressing arefrigerant, and an electric motor (45) driving the compressionmechanism (20). The electric motor (45) is disposed below thecompression mechanism (20), and is coupled to the compression mechanism(20) through a drive shaft (40) that is a rotational shaft. The electricmotor (45) is implemented as a brushless DC motor controlled by aninverter to adjust a rotational speed to be variable.

A discharge pipe (15) passes through and is attached to the upper endplate (12) that is a top of the casing (10). This discharge pipe (15)has its terminal end (the lower end in the figure) connected to thecompression mechanism (20). A suction pipe (14) passes through and isattached to the body (11) of the casing (10). This suction pipe (14) hasits terminal end (the right end in the figure) open toward a spacebetween the compression mechanism (20) and the electric motor (45) inthe casing (10).

The drive shaft (40) is disposed on the vertical center line of thecasing (10). The drive shaft (40) is a crank shaft including a mainshaft portion (41) and an eccentric portion (42). The eccentric portion(42) has a smaller diameter than the main shaft portion (41), and isformed on the upper surface of the main shaft portion (41). Theeccentric portion (42) is eccentric from the axial center of the mainshaft portion (41) by a predetermined dimension, and constitutes aneccentric pin. FIGS. 1 and 2 show a state where the main shaft portion(41) and the eccentric portion (42) are coaxially disposed. That isbecause FIGS. 1 and 2 are cross-sections viewed from a position in whichthe center of the main shaft portion (41) and the center of theeccentric portion (42) are on the same line. For example, if thecompressor is viewed from its lateral direction of FIGS. 1 and 2, thecenter of the main shaft portion (41) and the center of the eccentricportion (42) are eccentric from each other.

A lower bearing holder (48) is fixed to a portion adjacent to the lowerend of the body (11) of the casing (10). This lower bearing holder (48)rotatably supports the lower end of the main shaft portion (41) of thedrive shaft (40) through a sliding bearing (48 a).

The interior of the drive shaft (40) is provided with an oil supplypassage (44) extending vertically. The lower end of the main shaftportion (41) is provided with an oil supply pump (43). This oil supplypump (43) sucks refrigerating machine oil from the bottom of the casing(10). The refrigerating machine oil passes through the oil supplypassage (44) of the drive shaft (40) to be supplied to the slidingportion of the compression mechanism (20) and the bearing of the driveshaft (40).

The electric motor(45) is comprised of a stator (46) and a rotor (47).The stator (46) is fixed to the body (11) of the casing (10). The rotor(47) is coupled to the main shaft portion (41) of the drive shaft (40)to drive the drive shaft (40) in rotation.

The compression mechanism (20) includes a fixed scroll (21), an orbitingscroll (22), and a housing (23) fixing and supporting the fixed scroll(21). The fixed scroll (21) and the orbiting scroll (22) respectivelyinclude spiral laps (21 b, 22 b) meshing with each other on end plates(21 a, 22 a), which will be described later. The compression mechanism(20) is configured such that the orbiting scroll (22) rotateseccentrically relative to the fixed scroll (21).

The housing (23) is comprised of a body (23 a) and a bearing holder (23b). The body (23 a) is formed to be vertically continuous with thebearing holder (23 b), and the body (23 a) is fitted into and coupled tothe body (11) of the casing (10). The bearing holder (23 b) has asmaller diameter than the body (23 a), and protrudes downward from thebody (23 a). The bearing holder (23 b) rotatably supports the main shaftportion (41) of the drive shaft (40) through a sliding bearing (23 c).

The fixed scroll (21) is comprised of a fixed end plate (21 a), a fixedlap (21 b), and an edge portion (21 c). The fixed end plate (21 a) isformed to have a substantially disk shape. The fixed lap (21 b) standsnear the middle portion of the lower surface of the fixed end plate (21a), and is integrally formed with the fixed end plate (21 a). The fixedlap (21 b) is formed to have a spiral wall shape with a constant height.The edge portion (21 c) is a wall extending downward from the outerperipheral portion of the fixed end plate (21 a), and has a lowersurface overlapping with the upper surface of the body (23 a) of thehousing (23) to be fixed to the housing (23).

The orbiting scroll (22) is comprised of an orbiting end plate (22 a),an orbiting lap (22 b), and a boss (22 c). The orbiting end plate (22 a)is formed to have a substantially disk shape. The orbiting lap (22 b)stands on the upper surface of the orbiting end plate (22 a), and isintegrally formed with the orbiting end plate (22 a). The orbiting lap(22 b) is formed to have a spiral wall shape with a constant height, andto mesh with the fixed lap (21 b) of the fixed scroll (21). The boss (22c) extends downwardly from the lower surface of the orbiting end plate(22 a), and integrally formed with the orbiting end plate (22 a).

The eccentric portion (42) of the drive shaft (40) is inserted into theboss (22 c) through a sliding bearing (22 d). Therefore, if the driveshaft (40) rotates, the orbiting scroll (22) revolves around the axialcenter of the main shaft portion (41). The revolution radius of theorbiting scroll (22) is the same as the eccentricity of the eccentricportion (42), i.e., a distance from the axial center of the main shaftportion (41) to the axial center of the eccentric portion (42).

The orbiting end plate (22 a) is disposed in a first recess (23 d)provided to the upper end of the housing (23). The boss (22 c) isdisposed in a second recess (a crank chamber) (23 e) provided to thebody (23 a) of the housing (23). Although not shown, the Oldham couplingis disposed between the orbiting end plate (22 a) and the housing (23)to prevent the orbiting scroll (22) from rotating on its axis. The firstrecess (23 d) is formed large enough to allow the orbiting end plate (22a) to rotate eccentrically, and the second recess (23 e) is formed largeenough to allow the boss (22 c) to rotate eccentrically (the sizerelation therebetween is not considered on the figures).

FIG. 2 illustrates the shape of the fixed scroll and the shape of theorbiting scroll in a cross-section taken along line II-II of FIG. 1. Asshown in FIG. 2, the scroll compressor (1) in this embodiment has aso-called asymmetrical spiral structure. The number of turns or windingsof the spiral (the length of the spiral) differs between the fixed lap(21 b) and the orbiting lap (22 b). Specifically, the number of turns orwindings of the spiral of the fixed lap (21 b) is longer than that ofthe orbiting lap (22 b) by about a half turn. However, the outermostperiphery, i.e., the last turn or winding of the fixed lap (21 b) has noouter surface, and the portion of the fixed lap (21 b) corresponding tothe outer surface of the outermost periphery is continuous with the edgeportion (21 c) of the fixed scroll (21). The spiral of the fixed lap (21b) is ended such that its outer peripheral end faces its innerperipheral end longer than the outer peripheral end by one turn, and islocated near the outer peripheral end (turn or winding end) of theorbiting lap (22 b).

The compression mechanism (20) includes a plurality of compressionchambers (25 a, 25 b) in a space between the fixed end plate (21 a) andthe orbiting end plate (22 a). The compression chambers (25 a, 25 b) aredefined by allowing the fixed lap (21 b) to mesh with the orbiting lap(22 b). The plurality of the compression chambers (25 a, 25 b) include aplurality of first compression chambers (25 a) and a plurality of secondcompression chambers (25 b). The first compression chamber (25 a) isdefined by a space between the inner peripheral surface of the fixed lap(21 b) and the outer peripheral surface of the orbiting lap (22 b). Thesecond compression chamber (25 b) is defined by a space between theouter peripheral surface of the fixed lap (21 b) and the innerperipheral surface of the orbiting lap (22 b). In this embodiment, thenumber of turns or windings of the fixed lap (21 b) is greater than thatof the orbiting lap (22 b), and thus, the maximum capacity of the firstcompression chamber (25 a) is larger than that of the second compressionchamber (25 b).

As shown in FIGS. 1 and 2, the outer periphery of the fixed scroll (21)is provided with a suction port (29). This suction port (29) is opentoward a space above the compression mechanism (20). The suction port(29), along with the revolution of the orbiting scroll (22),intermittently communicates with the first compression chamber (25 a)and the second compression chamber (25 b).

The upper end of the fixed end plate (21 a) is provided with adepression (21 g), and a discharge cover (27) is attached to the uppersurface of the fixed end plate (21 a) to cover a depression (21 g). Aspace where the depression (21 g) is covered with the discharge cover(27) is a discharge chamber (28) communicating with the discharge pipe(15). A middle lower portion of the fixed end plate (21 a) is providedwith a discharge port (26) communicating with the discharge chamber(28). The discharge port (26), along with the revolution of the orbitingscroll (22), intermittently communicates with the first compressionchamber (25 a) and the second compression chamber (25 b). In thisembodiment, in the interior of the casing (10), both upper and lowerspaces (16) and (17) of the housing (23) are low-pressure spaces filledwith a low-pressure refrigerant.

In this embodiment, as shown in FIG. 3 that is an enlarged view of thecompression mechanism (20), a suction volume adjustment mechanism (30)is provided to adjust a suction completion position of the compressionchambers (25 a, 25 b) in the suction process of the compressionmechanism (20) to adjust the suction volume. This suction volumeadjustment mechanism (30) is configured to adjust the suction completionposition (at which the suction process is completed and a compressionprocess is started) in both the first and second compression chambers(25 a) and (25 b). Only one suction volume adjustment mechanism (30) isprovided to the outer spiral periphery within one turn, as shown in FIG.2. The suction volume adjustment mechanism (30) is configured to adjustthe suction volume by switching the suction completion position of thecompression chambers (25 a, 25 b) in the suction process between a firstposition and a second position in which the suction volume is smallerthan in the first position. The suction volume adjustment mechanism (30)is an opening/closing mechanism (31) allowing the first and secondcompression chambers (25 a) and (25 b) to switch between a communicatingstate and a shut-off state.

The opening/closing mechanism (31), as shown in FIG. 4 illustrating itscross-sectional structure, specifically includes a communication passage(32), a plunger (33), and an opening/closing drive mechanism (34). Thecommunication passage (32) allows the refrigerant to flow between thefirst and second compression chambers (25 a) and (25 b) when the firstand second compression chambers (25 a) and (25 b) communicate with eachother. The plunger (33) is switchable between a closed position in whichthe communication passage (32) is closed to move the suction completionposition to the first position, and an open position in which thecommunication passage (32) is open to move the suction completionposition to the second position. The opening/closing drive mechanism(34) switches the position of the plunger (33) between the open positionand the closed position.

As shown in FIG. 5, the plunger (33) is a cylindrical valve body, andhas an outer surface provided with a circumferential groove (33 d) thatis disposed on the oil passage (44) in the second position and isdeviated from the oil passage (44) in the first position.

The communication passage (32) is a stepped hole (32) formed in thefixed end plate (21 a). As shown in FIGS. 2 and 3, this stepped hole(32) is formed in the outer periphery of the spiral within one turn, andin an obliquely lower left position of the spiral center in the figure.As shown in FIGS. 2 and 3, this stepped hole (32) is comprised of alarger-diameter portion (32 a) opening toward the upper surface of thefixed end plate (21 a), and a smaller-diameter portion (32 b) having asmaller diameter than the larger-diameter portion (32 a). Thesmaller-diameter portion (32 b) constitutes the communication passage(32). This stepped hole (32) is formed such that the smaller-diameterportion (32 b) is located between teeth of the fixed lap (21 b). Thesmaller-diameter portion (32 b) is a circular hole having a largerdiameter than the thickness of the tooth of the orbiting lap (22 b).

A compression coil spring (a biasing member) (35) and the plunger (33)(see FIG. 5) having a tip end for opening/closing the smaller-diameterportion (32 b) are fitted in the stepped hole (32). As shown in FIG. 5,the plunger (33) includes a plug (33 a) fitted into the smaller-diameterportion (32 b), a spring holder (33 b) having a larger diameter than theplug (33 a) and mounting the compression coil spring (35) therein, and asealing portion (33 c) having a larger diameter than the spring holder(33 b), the plug (33 a), the spring holder (33 b), and the sealingportion (33 a) being continuously, integrally formed with one anotherfrom a tip end (the lower end of the figure). The sealing portion (33 c)is provided with the circumferential groove (33 d).

As shown in FIGS. 3 and 4, the opening/closing drive mechanism (34) iscomprised of the compression coil spring (35) and a switching valve (aswitching member) (36). The compression coil spring (35) biases theplunger (33) toward its open position. The switching valve (36) switchesthe state of the plunger (33) between a state in which a low pressure isapplied to the plunger (33) and a state in which a high pressure isapplied to the plunger (33) against the biasing force of the compressioncoil spring (35). If the switching valve (36) is switched to apply a lowpressure to the rear end surface (the upper surface) of the plunger(33), a force of the compression coil spring (35) trying to raise theplunger (33) is superior to a force trying to depress the plunger (33),and the communication passage (32) is opened. As a result, the firstcompression chamber (25 a) communicates with the second compressionchamber (25 b). If the switching valve (36) is switched to apply a highpressure to the rear end surface of the plunger (33), the force tryingto depress the plunger (33) is superior to the force of the compressioncoil spring (35) trying to raise the plunger (33), and the communicationpassage (32) is closed. As a result, the first compression chamber (25a) does not communicate with the second compression chamber (25 b).

Although the specific operation of the suction volume adjustmentmechanism (30) (opening/closing mechanism (31)) will be described later,if the suction volume adjustment mechanism (30) is operated with theplunger (33) in the closed position, the first and second compressionchambers (25 a) and (25 b) do not communicate with each other. Thus, anormal operation in which the refrigerant is compressed with a setsuction volume is performed. In contrast, if the suction volumeadjustment mechanism (30) is operated with the plunger (33) in the openposition, the first and second compression chambers (25 a) and (25 b)communicate with each other. Thus, an adjustment operation is performedin which the refrigerant is compressed with a less suction volume than aset value. In this embodiment, the rotational speed of the electricmotor (45) is faster during this adjustment operation than during thenormal operation.

In the casing (10), an oil reservoir (50) is formed in the bottom of thesecond recess (the crank chamber) (23 e) to reserve oil that haslubricated the bearing of the drive shaft (41) and other components. Thecompression mechanism (20) in this embodiment is provided with an oilpassage (51) communicating with the oil reservoir (50) and a suctionspace (25 s) of the compression chambers (25 a, 25 b). The oil passage(51) has one end communicating with the oil reservoir (50) formed in thecrank chamber (23 e) in the housing (23) of the compression mechanism(20), and the other end communicating with the suction space (25 s) ofthe compression mechanism (20). The oil passage (51), as shown in FIGS.3 and 6, is comprised of a lengthwise passage (52) adjacent to the oilreservoir, and a transverse passage (an arc-shaped passage) (53)adjacent to the suction space (25 s) of the compression mechanism (20).

The plunger (33) is disposed midway of the transverse passage (53) ofthe oil passage (51). The plunger (33) includes a switching portion(55). This switching valve (55) closes the oil passage (51) in theclosed position to allow the oil reservoir (50) not to communicate withthe suction space (25 s) of the compression chambers (25 a, 25 b), andopens the oil passage (51) in the open position to allow the oilreservoir (50) to communicate with the suction space (25 s) of thecompression chambers (25 a, 25 b). This switching portion (55) isconfigured as the circumferential groove (33 d) formed in the sealingportion (33 c). That is to say, in the open position in FIG. 3, the oilpassage (51) communicates with the oil reservoir (50) and the suctionspace (25 s) of the compression chambers (25 a, 25 b) through thecircumferential groove (33 d). In contrast, in the closed position whichis not shown, the sealing portion (33 c) blocks the oil passage (51),and thus, the oil reservoir (50) does not communicate with the suctionspace (25 s) of the compression chambers (25 a, 25 b), and no oil issupplied from the oil reservoir (50) to the suction space (25 s) of thecompression chambers (25 a, 25 b).

Operation

Next, it will be described how the scroll compressor (1) stated above isoperated.

First, if the electric motor (45) is driven, the drive shaft (40)rotates and the orbiting scroll (22) revolves relative to the fixedscroll (21). At that time, the Oldham coupling (not shown) prevents thefixed scroll (21) from rotating on its axis.

Along with the revolution of the orbiting scroll (22), volumes of thecompression chambers (25 a, 25 b) increase and decrease repeatedly andperiodically. In the compression chambers (25 a, 25 b), the refrigerantin the refrigerant circuit is sucked from the suction pipe (14) througha suction passage (not shown) and the suction port (29) into thecompression chambers (25 a, 25 b) when the volume of a portion,communicating with the suction port (29), of the compression chambers(25 a, 25 b) is increased, and the refrigerant in the refrigerantcircuit is compressed and discharged from the discharge port (26) to thedischarge chamber (28) when the volume of a portion in which a suctionside is closed decreases. The refrigerant in the discharge chamber (28)is supplied from the discharge pipe (15) to the condenser in therefrigerant circuit.

Operation of Compression Mechanism During Normal Operation

The refrigerant suction and compression operations of the compressionmechanism (20) when the suction volume adjustment mechanism (30) is notoperated (during the normal operation) will be described with referenceto FIGS. 7 to 12. During the normal operation, the plunger (33) of theopening/closing mechanism (31) is in the closed position, and closes thecommunication passage (32), and the first compression chamber (25 a)does not communicate with the second compression chamber (25 b). FIGS. 7to 12 are cross-sectional views of six stages of the operation state ofthe compression mechanism (20), and illustrate that the orbiting scroll(22) revolves at a predetermined angle in the clockwise direction in thefigures.

First, in the first operation state shown in FIG. 7, the spiral of theorbiting lap (22 b) is ended between the teeth of the fixed lap (21 b),and both the first compression chamber (25 a-0) and the secondcompression chamber (25 b-0) which are in the outermost peripherycommunicate with a low-pressure side and the suction port (29).Regarding the first compression chamber (25 a), the outer peripheralsurface of the orbiting lap (22 b) is substantially in contact with theinner peripheral surface of the fixed lap (21 b) at the point P on thecenter line Y of the figure. “Contact” in this context means a statewhere, although there is a gap of submicron order, even if therefrigerant is leaked, no problem occurs because of formation of the oilfilm. The compression process is started in a portion (25 a-1) that isin the inner side (a side closer to the start point of the spiral)relative to the contact point (sealing point) P1.

From this state, the orbiting scroll (22) revolves in the clockwisedirection in the figure to be in the second operation state in FIG. 8.At that time, the inner peripheral surface of the spiral end of theorbiting lap (22 b) is in contact with the outer peripheral surface ofthe fixed lap (21 b), and its contact point (sealing point) P2 is thesuction completion position of the second compression chamber (25 b-1).At that time, the suction process in which the volume is increased isstill being performed in the first compression chamber (25 a-0) that isin the outermost periphery, and no sealing point at the spiral end isformed.

From this state, if the orbiting scroll (22) revolves to be in the thirdoperation state in FIG. 9, the volume of the second compression chamber(25 b-1) is reduced to start the compression process of the refrigerantin the second compression chamber (25 b-1), and the volume of the firstcompression chamber (25 a-0) that is in the outermost periphery isfurther expanded to allow the suction process of the refrigerant toproceed in the first compression chamber (25 a-0). In the fourthoperation state in FIG. 10, the compression process further proceeds inthe second compression chamber (25 b-1), and the suction process furtherproceeds in the first compression chamber (25 a-0) that is in theoutermost periphery. Regarding the second compression chamber (25 b),the second compression chamber (25 b-0) is newly formed at a portioncloser to the turn or winding end of the spiral relative to the secondcompression chamber (25 b-1) in which the compression process is beingperformed, and the suction process is started in the newly formed secondcompression chamber (25 b-0).

In the fifth operation state shown in FIG. 11, the suction processfurther proceeds in the second compression chamber (25 b-0) that is inthe outermost periphery, the outer peripheral surface of the turn orwinding end of the spiral of the orbiting lap (22 b) is in contact withthe inner peripheral surface of the fixed lap (21 b), and its contactpoint (sealing point) P1 is the suction completion position of the firstcompression chamber (25 a-1). In the sixth operation state shown in FIG.12, the compression process proceeds in the first compression chamber(25 a-1) formed in the state of FIG. 11, and the suction processproceeds in the second compression chamber (25 b-0) that is in theoutermost periphery. Then, the process goes back to the first operationstate shown in FIG. 7, the first compression chamber (25 a-0) is newlyformed at a portion closer to the outer periphery (the turn or windingend of the spiral) of the first compression chamber (25 a-1) in whichthe compression process is being performed.

Thereafter, the operations in FIGS. 7 to 12 are repeatedly performed,the first compression chamber (25 a-1) in the middle of compression andthe second compression chamber (25 b-1) are moved toward the inner sideof the spiral while reducing its volume, and the first compressionchamber (25 a-2) and the second compression chamber (25 b-2) change tothe state immediately before the discharge. When the first compressionchamber (25 a-2) and the second compression chamber (25 b-2) are movedto the innermost peripheral side to have the minimum volume, theycommunicate with the discharge port (26), and the refrigerant isdischarged from the compression mechanism (20).

During the normal operation, in the suction volume adjustment mechanism(30), the plunger (33) is in the closed position and the oil passage(51) is blocked. As a result, the oil reservoir (50) does notcommunicate with the suction space (25 s) of the compression chambers(25 a, 25 b). Therefore, during the normal operation at the highoperation capacity, the discharge of the oil is small, and along withthis, no oil is supplied from the oil reservoir (50) to the compressionchambers (25 a, 25 b), and oil is not excessively supplied to thecompression chambers.

Operation of Compression Mechanism During Adjustment Operation

Likewise, the refrigerant suction and compression operations of thecompression mechanism (20) when the suction volume adjustment mechanism(30) is operated (during the adjustment operation) will be describedwith reference to FIGS. 7 to 12. During the adjustment operation, in theopening/closing mechanism (31) that is the suction volume adjustmentmechanism (30), the plunger (33) is in the open position and opens thesmaller-diameter portion (32 b) of the communication passage (32). Thisallows the first compression chamber (25 a) to communicate with thesecond compression chamber (25 b).

First, in the first operation state shown in FIG. 7, both the firstcompression chamber (25 a-0) and the second compression chamber (25 b-0)in the outermost periphery communicate with the low-pressure side andthe suction port (29), which is the same as the normal operation. Duringthe normal operation, the outer peripheral surface of the orbiting lap(22 b) is in contact with the inner peripheral surface of the fixed lap(21 b) at the point P1 on the center line Y of the figure, and the firstcompression chamber (25 a-1) in the inner side (the side closer to thewinding start point of the spiral) relative to the contact point(sealing point) P1 is already closed. In contrast, the first compressionchamber (25 a-1) during this operation communicates with the secondcompression chamber (25 b-0) that is in the outermost periphery in themiddle of the suction process through the communication passage (32).Accordingly, the first compression chamber (25 a-1) is in a positionprior to the suction completion position, and is in the middle of thesuction process as well as the second compression chamber (25 b).

In the second operation state in FIG. 8, the contact point P1 betweenthe inner peripheral surface of the fixed lap (21 b) and the outerperipheral surface of the orbiting lap (22 b) is displaced to a positionimmediately rearward of the communication passage (32) of theopening/closing mechanism (31). Therefore, the contact point (sealingpoint) P1 at that time is the suction completion position of the firstcompression chamber (25 a-1). In this position, the second compressionchamber (25 b-1) that is located in the outermost periphery and isclosed during the normal operation communicates with the firstcompression chamber (25 a-0) that is located in the outermost peripheryand is formed in the outside of the spiral of the first compressionchamber (25 a-1) that is in the compression process through thecommunication passage (32). The first compression chamber (25 a-0) thatis located in the outermost periphery is in the middle of the suctionprocess, and thus, the second compression chamber (25 b) is in aposition prior to the suction completion position.

This position is also seen in the third operation state shown in FIG. 9and the fourth operation state shown in FIG. 10. The second compressionchamber (25 b-1) is in the position prior to the suction completionposition, and a sealing point closer to the turn or winding end is notformed yet. At that time, the first compression chamber (25 a-0) that isthe outermost periphery is also in the middle of the suction process. Inthe fourth operation state shown in FIG. 10, the second compressionchamber (25 b-0) is started to be newly formed in the outside of thespiral of the second compression chamber (25 b-1).

In the fifth operation state shown in FIG. 11, the contact point P2between the outer peripheral surface of the fixed lap (21 b) and theinner peripheral surface of the orbiting lap (22 b) passes through thecommunication passage (32) of the opening/closing mechanism (31).Therefore, the contact point P2 at that time is the sealing point of thesecond compression chamber (25 b-1), and the compression process isstarted in the second compression chamber (25 b-1). In this state,although the suction process in the first compression chamber (25 a-1)that is in the outermost periphery is completed in the normal operation,the first compression chamber (25 a-1) that is in the outermostperiphery in the adjustment operation communicates with the low-pressureside through the second compression chamber (25 b-0) that is in theoutermost periphery, and thus, is in the middle of the suction process.This also occurs in the sixth operation state in FIG. 12, and the sameoccurs if the process goes back to the first operation state in FIG. 7.

As can be seen, the communication passage (32) of the opening/closingmechanism (31) is opened, and thus, the volume of the first compressionchamber (25 a) and the volume of the second compression chamber (25 b)is smaller than during the normal operation. As a result, a compressionratio is smaller than during the normal operation, and if its suctionpressure is the same as during the normal operation, the dischargepressure is decreased.

During this adjustment operation, the rotational speed of the electricmotor (45) is faster than during the normal operation, and thus,substantially the same performance of the scroll compressor (1) as inthe normal operation can be achieved.

During the adjustment operation, in the suction volume adjustmentmechanism (30), the plunger (33) is in the open position and the oilpassage (51) is opened to allow the oil reservoir (50) to communicatewith the suction space (25 s) of the compression chambers (25 a, 25 b).Therefore, during the adjustment operation at the low operationcapacity, the performance is adjusted to provide the same capacity, andthus, the rotational speed is faster than in the case where noadjustment is made. This increases the supply amount of the oil to thecompression chambers (25 a, 25 b), and in addition, allows oil from theoil reservoir (18, 50) to the compression chambers (25 a, 25 b). As aresult, oil is sufficiently supplied to the compression chambers (25 a,25 b).

Advantages of First Embodiment

According to this embodiment, if only the adjustment operation at thelow operation capacity is performed, oil is not sufficiently supplied tothe compression chambers (25 a, 25 b), and the oil film having athickness necessary for the compression mechanism (20) is not formed,resulting in performance degradation. However, if the oil passage (51)is opened and the oil reservoir (50) communicates with the suction space(25 s) of the compression chambers (25 a, 25 b), oil is sufficientlysupplied to the compression chambers (25 a, 25 b). Thus, this canimprove performance during the adjustment operation.

Variation of First Embodiment

As shown in FIGS. 13 and 14, the oil passage (51) may include a passage(fixed scroll inner passage (53)) entirely passing through the inside ofthe fixed scroll (21) to communicate with the plunger (33) and thesuction space (25 s) of the compression mechanism (20). In thisvariation, the suction pipe (14) is connected to the suction port (29),and the transverse passage (53) of the oil passage (51) communicateswith the suction port (29). Such a configuration allows the oil in theoil reservoir (50) to mix with the suction refrigerant and to besupplied to the compression chamber (25).

According to this variation, if only the adjustment operation at the lowoperation capacity is performed, oil is not sufficiently supplied to thecompression chambers (25 a, 25 b), and the oil film having a thicknessnecessary for the compression mechanism is less likely to be formed,resulting in performance degradation. However, in this variation, if theoil passage (51) is in the state in FIG. 13 to be opened and the oilreservoir (50) communicates with the suction space (25 s) of thecompression chambers (25 a, 25 b), oil is sufficiently supplied to thecompression chambers (25 a, 25 b). Thus, this can improve performanceduring the adjustment operation.

Second Embodiment

Next, a second embodiment will be described.

In the second embodiment, as shown in FIGS. 15 and 16, the oil passage(51) includes an oil passage (55) closer to the orbiting scroll(hereinafter referred to as “the orbiting-scroll-side oil passage(55)”), and an oil passage (52) closer to the fixed scroll (hereinafterreferred to as “the fixed-scroll-side oil passage (52)”) communicatingwith the orbiting-scroll-side oil passage (55). The orbiting-scroll-sideoil passage (55) has one end communicating with the fixed-scroll-sideoil passage (51), and the other end opposite to one end andcommunicating with the oil reservoir (18). Specifically, the end of theorbiting-scroll-side oil passage (55), which is opposite to one endcommunicating with the fixed-scroll-side oil passage (52), communicateswith the oil reservoir (18) in the lower portion of the casing (10)through the oil supply passage (44) formed inside the drive shaft (41).An end of the fixed-scroll-side oil passage (52), which is opposite toan end communicating with the orbiting-scroll-side oil passage (55),communicates with the suction space (25 s) of the compression mechanism(20).

According to this second embodiment, if only the adjustment operation atthe low operation capacity is performed, oil is not sufficientlysupplied to the compression chambers (25 a, 25 b), and the oil filmhaving a thickness necessary for the compression mechanism is lesslikely to be formed, resulting in performance degradation. However, inthe second embodiment, if the oil passage (51) is in the state in FIG.16 to be opened and the oil reservoir (18) communicates with the suctionspace (25 s) of the compression chambers (25 a, 25 b), oil issufficiently supplied to the compression chambers (25 a, 25 b). Thus,this can improve performance during the adjustment operation.

Third Embodiment

Next, a third embodiment will be described.

In the third embodiment, as shown in FIG. 17, the oil passage (51) hasone end communicating with the oil reservoir (18) formed inside thecasing (10), and the other end communicating with the suction space (25s) of the compression mechanism (20). Specifically, the oil passage (51)has an oil supply pipe (56) extending upward from the oil reservoir (18)inside the casing (10) and communicating with the plunger (33). This oilsupply pipe (56) communicates with the transverse passage (53). In theoil passage (51), a space (the transverse passage (53)) between theplunger (33) and a suction side of the compression chamber (25) is thesame as, or similar to, that of the variation of the first embodimentand the second embodiment.

The other configuration of this embodiment is the same as, or similarto, that of the second embodiment.

According to this third embodiment, if only the adjustment operation atthe low operation capacity is performed, oil is not sufficientlysupplied to the compression chambers (25 a, 25 b), and the oil filmhaving a thickness necessary for the compression mechanism is lesslikely to be formed, resulting in performance degradation. However, inthe third embodiment, if the oil passage (51) is in the state in FIG. 17to be opened and the oil reservoir (18) communicates with the suctionspace (25 s) of the compression chambers (25 a, 25 b), oil issufficiently supplied to the compression chambers (25 a, 25 b). Thus,this can improve performance during the adjustment operation.

Fourth Embodiment

Next, a fourth embodiment will be described.

In the fourth embodiment, as shown in FIG. 18, the oil passage (51) hasone end communicating with an oil supply pump (43 a) provided to thedrive shaft (41), and the other end communicating with the suction space(25 s) of the compression mechanism (20). Specifically, the oil passage(51) has an oil supply pipe (57) extending upward from the oil supplypump (43 a) provided to the lower end of the drive shaft (41) andcommunicating with the plunger (33). This oil supply pipe (57)communicates with the transverse passage (53). In the oil passage (51),a space (the transverse passage (53)) between the plunger (33) and asuction side of the compression chamber (25) is the same as, or similarto, that of the variation of the first embodiment and the secondembodiment.

The other configuration of this embodiment is the same as, or similarto, that of the third embodiment.

According to this fourth embodiment, if only the adjustment operation atthe low operation capacity is performed, oil is not sufficientlysupplied to the compression chambers (25 a, 25 b), and the oil filmhaving a thickness necessary for the compression mechanism is lesslikely to be formed, resulting in performance degradation. However, inthe fourth embodiment, if the oil passage (51) is in the state in FIG.18 to be opened and the oil reservoir (18) communicates with the suctionspace (25 s) of the compression chambers (25 a, 25 b), oil issufficiently supplied to the compression chambers (25 a, 25 b). Thus,this can improve performance during the adjustment operation.

Fifth Embodiment

Next, a fifth embodiment will be described.

In the fifth embodiment, as shown in FIGS. 19 to 21, the oil passage(51) includes a fixed scroll outer passage (58) passing through thespace (17) formed outside the fixed scroll (21) inside the casing (10)to communicate with the plunger (33) and the suction space (25 s) of thecompression mechanism (20). In the fifth embodiment, the fixed scroll(21) is provided with a gas discharge passage (60) through which therefrigerant gas is discharged from the compression chambers (25 a, 25 b)to the space (17).

According to this configuration, as shown in FIG. 20, when the plunger(33) is open, the refrigerant gas is discharged from the compressionchambers and oil is also discharged from the transverse passage (53) tothe space (17). The refrigerant gas and the oil are mixed with eachother and sucked into the suction space (25 s). In contrast, as shown inFIG. 21, when the plunger (33) is closed, no refrigerant gas isdischarged from the compression chambers (25 a, 25 b) to the space (17),and no oil is discharged from the transverse passage (53) to the space(17).

According to this fifth embodiment, if only the adjustment operation atthe low operation capacity is performed, oil is not sufficientlysupplied to the compression chambers (25 a, 25 b), and the oil filmhaving a thickness necessary for the compression mechanism is lesslikely to be formed, resulting in performance degradation. However, inthe fifth embodiment, if the oil passage (51) is in the state in FIG. 20to be opened and the oil reservoir (18) communicates with the suctionspace (25 s) of the compression chambers (25 a, 25 b), oil issufficiently supplied to the compression chambers (25 a, 25 b). Thus,this can improve performance during the adjustment operation. The highspeed operation can reduce performance degradation and oil loss.

Sixth Embodiment

A sixth embodiment of the present disclosure is an example and has thesame configuration as the fifth embodiment, except the configuration forthe oil passage (51). Specifically, as shown in FIGS. 22 and 23, the oilpassage (51) includes a fixed scroll outer passage (58) passing throughthe space (17) formed outside the fixed scroll (21) inside the casing(10) to communicate with the plunger (33) and the suction space (25 s)of the compression mechanism (20). In the sixth embodiment, the fixedscroll (21) is provided with a gas discharge passage (60) through whichthe refrigerant gas is discharged from the compression chambers (25 a,25 b) to the space (17). In this sixth embodiment, the end of thetransverse passage (53) is closed and the transverse passage (53)communicates with the gas discharge passage (60) through an oil mixpassage (53 a).

According to this configuration, as shown in FIG. 23, when the plunger(33) is open, the refrigerant gas is discharged from the compressionchambers, and the oil is mixed with the gas flowing through the gasdischarge passage (60) to be discharged into the space (17). Therefrigerant gas and the oil are mixed together, and are sucked into thesuction space (25 s). Although not shown, when the plunger (33) isclosed, no gas is discharged from the compression chambers (25 a, 25 b)into the space (17).

According to this sixth embodiment, if only the adjustment operation atthe low operation capacity is performed, oil is not sufficientlysupplied to the compression chambers (25 a, 25 b), and the oil filmhaving a thickness necessary for the compression mechanism is lesslikely to be formed, resulting in performance degradation. However, inthe sixth embodiment, if the oil passage (51) is in the state in FIG. 23to be opened and the oil reservoir (18) communicates with the suctionspace (25 s) of the compression chambers (25 a, 25 b), oil issufficiently supplied to the compression chambers (25 a, 25 b). Thus,this can improve performance during the adjustment operation.

Other Embodiments

The above-described embodiment may be modified as follows.

For example, the above embodiments are the examples where the presentdisclosure is applied to the asymmetrical spiral structure. The presentdisclosure may also be applied to a scroll compressor having asymmetrical spiral structure. In this case, the suction volumeadjustment mechanism (30) having the same or similar configuration as orto those in the above embodiments may be provided to each symmetricalposition relative to the center of the spiral. Such a configurationallows the compression mechanism (20) having the symmetrical spiralstructure to adjust the suction completion positions of the first andsecond compression chambers (25 a) and (25 b) relative to the center ofthe spiral, while controlling the flow of the oil. As a result, the sameor similar advantages in the above embodiments can also be obtained.

In the above embodiments, the present disclosure is applied to thescroll compressor. However, the present disclosure is not limited to thescroll compressor. For example, the present disclosure may also beapplied to a rolling piston compressor or an oscillating pistoncompressor.

Further, in the above embodiments, as shown in FIG. 24, a sealing member(33 e) may be provided to both sides of the circumferential groove (33d) in the outer peripheral surface of the plunger (33). In this case,the sealing portion (33 c) of the plunger (33) has a sealing mountgroove (33 f) at both sides of the circumferential groove (33 d) in thecircumferential direction, and the ring-shaped sealing member (33 e) ismounted on the sealing mount groove (33 f).

Note that the foregoing description of the embodiments is a merelypreferred example in nature, and is not intended to limit the scope,application, or uses of the present disclosure.

INDUSTRIAL APPLICABILITY

As can be seen from the foregoing description, the present disclosure isuseful for, in a compressor including a suction bypass mechanismconfigured to change a suction completion position to adjust a suctionvolume, a technique of solving lubricant shortage in a compressionmechanism.

DESCRIPTION OF REFERENCE CHARACTERS

-   1 Scroll Compressor-   10 Casing-   18 Oil Reservoir-   21 Fixed Scroll-   22 Orbiting Scroll-   23 Housing-   23 e Crank Chamber-   25 a Compression Chamber-   25 b Compression Chamber-   25 s Suction Space-   30 Suction Volume Adjustment Mechanism-   33 Plunger-   33 d Circumferential Groove-   33 e Sealing Member-   43 a Oil Supply Pump-   50 Oil Reservoir-   51 Oil Passage-   52 Fixed-scroll-side Oil Passage (Fixed Scroll Inner Passage)-   53 Fixed-scroll-side Oil Passage (Fixed Scroll Inner Passage)-   53 a Oil Mix Passage-   55 Orbiting-scroll-side Oil Passage-   56 Oil Supply Pipe-   57 Oil Supply Pipe-   58 Fixed Scroll Outer Passage-   60 Gas Discharge Passage-   65 Switching Portion

1. A compressor comprising: a compression mechanism; and a casinghousing the compression mechanism, the compression mechanism including asuction volume adjustment mechanism capable of switching a suctioncompletion position of a compression chamber in a suction processbetween a first position and a second position in which a suction volumeis smaller than in the first position, the suction volume adjustmentmechanism including a plunger switchable between a closed position inwhich the suction completion position is moved to the first position andan open position in which the suction completion position is moved tothe second position, the compressor further including an oil passagearranged to allow an oil reservoir formed inside the casing and asuction space of the compression chamber to communicate with each other,and the plunger being disposed midway along the oil passage, andincluding a switching portion closing the oil passage in the closedposition to allow the oil reservoir not to communicate with the suctionspace of the compression chamber, and opening the oil passage in theopen position to allow the oil reservoir to communicate with the suctionspace of the compression chamber.
 2. The compressor of claim 1, whereinthe compression mechanism includes a fixed scroll, and an orbitingscroll meshing with the fixed scroll to compress a working fluid.
 3. Thecompressor of claim 2, wherein the oil passage has one end communicatingwith the oil reservoir and an other end communicating with the suctionspace of the compression mechanism, and the oil reservoir is formed in acrank chamber that is a space inside the housing of the compressionmechanism.
 4. The compressor of claim 2, wherein the oil passageincludes an orbiting-scroll-side oil passage and a fixed-scroll-side oilpassage communicating with the orbiting-scroll-side oil passage, theorbiting-scroll-side oil passage has one end communicating with thefixed-scroll-side oil passage, and an other end opposite to the one endthereof communicating with the oil reservoir, and the fixed-scroll-sideoil passage has one end communicating with the orbiting-scroll-side oilpassage, and an other end opposite to the one end thereof communicatingwith the suction space of the compression mechanism.
 5. The compressorof claim 2, wherein the oil passage has an oil supply pipe having oneend communicating with the oil reservoir, and an other end communicatingwith the suction space of the compression mechanism.
 6. The compressorof claim 2, wherein the oil passage has an oil supply pipe having oneend communicating with an oil supply pump provided to a drive shaft ofthe compression mechanism, and an other end communicating with thesuction space of the compression mechanism.
 7. The compressor of claim3, wherein the oil passage has a fixed scroll inner passage passingthrough an interior of the fixed scroll to communicate with the plungerand the suction space of the compression mechanism.
 8. The compressor ofclaim 3, wherein the oil passage has a fixed scroll outer passagepassing through a space formed outside the fixed scroll and inside thecasing to communicate with the plunger and the suction space of thecompression mechanism.
 9. The compressor of claim 3, wherein the suctionvolume adjustment mechanism has a discharge passage arranged todischarge the working fluid from the plunger in the second position intoa space formed outside the fixed scroll and inside the casing, and theoil passage has an oil mix passage having one end communicating with theplunger, and an other end communicating with the discharge passage. 10.The compressor of claim 1, wherein the plunger is a cylindrical valvebody, and has an outer surface provided with a circumferential groovethat is disposed on the oil passage in the second position and isdeviated from the oil passage in the first position.
 11. The compressorof claim 10, wherein the plunger includes a sealing member at both sidesof the circumferential groove formed in the outer surface of theplunger.
 12. The compressor of claim 4, wherein the oil passage has afixed scroll inner passage passing through an interior of the fixedscroll to communicate with the plunger and the suction space of thecompression mechanism.
 13. The compressor of claim 4, wherein the oilpassage has a fixed scroll outer passage passing through a space formedoutside the fixed scroll and inside the casing to communicate with theplunger and the suction space of the compression mechanism.
 14. Thecompressor of claim 4, wherein the suction volume adjustment mechanismhas a discharge passage arranged to discharge the working fluid from theplunger in the second position into a space formed outside the fixedscroll and inside the casing, and the oil passage has an oil mix passagehaving one end communicating with the plunger, and an other endcommunicating with the discharge passage.
 15. The compressor of claim 5,wherein the oil passage has a fixed scroll inner passage passing throughan interior of the fixed scroll to communicate with the plunger and thesuction space of the compression mechanism.
 16. The compressor of claim5, wherein the oil passage has a fixed scroll outer passage passingthrough a space formed outside the fixed scroll and inside the casing tocommunicate with the plunger and the suction space of the compressionmechanism.
 17. The compressor of claim 5, wherein the suction volumeadjustment mechanism has a discharge passage arranged to discharge theworking fluid from the plunger in the second position into a spaceformed outside the fixed scroll and inside the casing, and the oilpassage has an oil mix passage having one end communicating with theplunger, and an other end communicating with the discharge passage. 18.The compressor of claim 6, wherein the oil passage has a fixed scrollinner passage passing through an interior of the fixed scroll tocommunicate with the plunger and the suction space of the compressionmechanism.
 19. The compressor of claim 6, wherein the oil passage has afixed scroll outer passage passing through a space formed outside thefixed scroll and inside the casing to communicate with the plunger andthe suction space of the compression mechanism.
 20. The compressor ofclaim 6, wherein the suction volume adjustment mechanism has a dischargepassage arranged to discharge the working fluid from the plunger in thesecond position into a space formed outside the fixed scroll and insidethe casing, and the oil passage has an oil mix passage having one endcommunicating with the plunger, and an other end communicating with thedischarge passage.